In the development process of communications technologies, to increase spectrum resource utilization, a carrier aggregation (CA) technology is introduced to a Long Term Evolution (LTE) communications system.
The CA technology is a technology that acquires higher bandwidth by aggregating multiple continuous or discontinuous Component Carriers (CCs). The multiple aggregated CCs include one Primary Component Carrier (PCC) and at least one Secondary Component Carrier (SCC). A carrier that a UE is initially connected to is a PCC, and other carriers are SCCs.
Feedback information such as acknowledgement (ACK) or negative acknowledgement (NACK) of a downlink transmission block of the SCC can only be fed back over a Physical Uplink Control Channel (PUCCH) of the PCC. However, with the wide deployment of micro base stations, the density of base stations increases. A PCC for which one CC serves as 8 CCs or even more CCs has wide application scenarios. In this case, a demand for a PUCCH resource greatly increases.
For example, currently, to ensure that PUCCH resources used by user equipments on different SCCs do not conflict with each other during SCC scheduling, an independent PUCCH resource needs to be allocated to each SCC. Therefore, as a quantity of SCCs increases, PUCCH resource consumption of a PCC increases linearly. In addition, a PUCCH resource itself is not used for data transmission. In this way, as PUCCH resource consumption increases linearly, an uplink throughput supported by the PCC dramatically decreases, and system performance is deteriorated.